Association between paraoxonase-1 gene polymorphisms and risk of metabolic syndrome

Paraoxonase-1 (PON1), a high-density lipoprotein (HDL) associated enzyme, is involved in the metabolism and detoxification of insecticides and pesticides. Three polymorphisms within the PON1 gene affect the enzyme activity. Two of these (L55M and Q192R) are located at the coding region and the third (–107C/T) is in promoter region. We performed a case–control study in order to elucidate the possible contribution of variability within PON1 at three mentioned positions to the risk of MS in a South-East Iranian population. DNA was isolated from peripheral blood of patients (N = 119) with MS and healthy controls (N = 201). Allelic polymorphisms at positions Q192R, L55M and –107C/T in the PON1 gene were studied by Amplification Refractory Mutation System (ARMS)-PCR. It was observed that genotypes RR and QR + RR of Q192R locus significantly increased the risk of MS (OR = 2; 95% CI: 1.17–3.40, P = 0.0001 and OR = 1.62; 95% CI: 1.0–2.63; P = 0.05, respectively). The risk in patients with MM and LM + MM genotypes at the L55M locus was marginal (OR = 1.33; 95% CI: 0.68–1.85; P = 0.34 and OR = 1.12; 95% CI: 0.68–1.85; P = 0.73 respectively). The CC genotype at –107C/T locus also increased the risk of metabolic syndrome, but was not significant. This association was somewhat stronger when combined genotypes at Q192R and L55M loci were analyzed (OR = 3.30; 95% CI: 1.34–8.24; P = 0.007). Our results, in this first study, provide evidence for association of PON1 gene polymorphisms with the risk for metabolic syndrome.     

The role of heme oxygenase-1 promoter polymorphisms in human disease

Heme oxygenase (HO) seems to be a novel protective factor with potent anti-inflammatory, anti-oxidant, and anti-proliferative effects. HO-1, the inducible isoform, is expressed in various tissues and is upregulated by multiple stimuli. However, humans differ quantitatively in their ability to mount an HO-1 response, modulated by two potentially functional polymorphisms in the HO-1 gene promoter region. From several studies it seems that the ability of a patient with certain genotypes to respond strongly in terms of upregulating HO-1 may be an important endogenous protective factor. In the present article we systematically review the hitherto published evidence that promoter polymorphisms in the HO-1 gene exert functional importance by influencing the level of HO-1 expression in different organ systems.     

Association of susceptibility to the development of lung adenocarcinoma with the heme oxygenase-1 gene promoter polymorphism

Heme oxygenase-1 (HO-1) acts in cytoprotection against oxidants and aromatic hydrocarbons in cigarette smoke. A (GT)_n dinucleotide repeat in the 5-flanking region of the human HO-1 gene (alias HMOX1) reduces HO-1 inducibility and shows length polymorphism, which is grouped into three classes: class S (<27 GT), class M (27–32 GT), and class L (33 GT) alleles. To investigate the correlation between the HO-1 gene polymorphism and the development of lung adenocarcinoma, we screened 151 Japanese patients with lung adenocarcinoma and 153 control subjects. Patients and control subjects were frequency-matched by age, gender, smoking history and proportion of chronic pulmonary emphysema. The proportion of class L allele frequencies, as well as that of genotypic frequencies in L allele carriers (LL, LM, and LS), were significantly higher in patients with lung adenocarcinoma than those of control subjects. The adjusted odds ratio (OR) for lung adenocarcinoma with class L allele vs non-L allele (M+S) was 1.6 [95% confidence interval (CI) 1.0–2.5, P=0.03] and that with L allele carriers vs. non-L allele carriers was 1.8 (95% CI 1.1–3.0, P=0.02). Furthermore, the risk of lung adenocaricinoma for L allele carriers versus non-L allele carriers was much increased in the group of male smokers (OR=3.3, 95% CI 1.5–7.4, P=0.004). However, in the female non-smokers, the proportion of L allele carriers did not differ between patients and control subjects (OR=0.93, 95% CI 0.4–2.0, P=0.85). These findings suggest that the large size of a (GT)_n repeat in the HO-1 gene promoter may be associated with the development of lung adenocarcinoma in Japanese male smokers.     

Epoxyeicosatrienoic acids and heme oxygenase-1 interaction attenuates diabetes and metabolic syndrome complications

MSCs are considered to be the natural precursors to adipocyte development through the process of adipogenesis. A link has been established between decreased protective effects of EETs or HO-1 and their interaction in metabolic syndrome. Decreases in HO-1 or EET were associated with an increase in adipocyte stem cell differentiation and increased levels of inflammatory cytokines. EET agonist (AKR-I-27-28) inhibited MSC-derived adipocytes and decreased the levels of inflammatory cytokines. We further describe the role of CYP-epoxygenase expression, HO expression, and circulating cytokine levels in an obese mouse, ob/ob(-/-) mouse model. Ex vivo measurements of EET expression within MSCs derived from ob/ob(-/-) showed decreased levels of EETs that were increased by HO induction. This review demonstrates that suppression of HO and EET systems exist in MSCs prior to the development of adipocyte dysfunction. Further, adipocyte dysfunction can be ameliorated by induction of HO-1 and CYP-epoxygenase, i.e. EET.     

Interaction between heme oxygenase-1 and -2 proteins

The three isoforms of heme oxygenase (HO), the rate-limiting enzyme in heme degradation, are the products of different genes that show marked differences in regulation and expression. Why is there redundancy in the heme degradation pathway, and why are there differences in tissue expression of HO isoenzymes are unanswered questions? An interaction between HO-1 and HO-2 is suspected by the co-localization of these enzymes in the lung and regions of the brain. Using multiple models and assays, we demonstrated an interaction between HO-1 and HO-2 at amino acids 0-45 of HO-2 and amino acids 58-80 of HO-1. The latter corresponds to a highly conserved, hydrophilic, and exposed region of the protein. Furthermore, the observed activity of the HO-1.HO-2 complex was lower than that expected from the sum of HO-1- and HO-2-derived activities, suggesting that this interaction serves to limit HO enzymatic activity. We speculate that this HO-1.HO-2 protein interaction may promote non-enzymatic functions of HO.     

Association between PIN1 promoter polymorphisms and risk of nasopharyngeal carcinoma

Peptidylprolyl cis/trans isomerase, NIMA-interacting 1 (PIN1) plays an important role in cell transformation and oncogenesis. Association between PIN1 promoter polymorphisms and cancer risk was reported in several cancers. This study aimed to evaluate the association between two single nucleotide polymorphisms (SNPs, ?667T>C, rs2233679 and ?842G>C, rs2233678) on PIN1 promoter and risk of nasopharyngeal carcinoma (NPC). The two SNPs were genotyped using polymerase chain reaction-restriction fragment length polymorphism in a total of 334 native Chinese subjects consisting of 178 cases and 156 controls. The results indicated that the ?667CT heterozygote and ?667CC homozygote exhibited a significantly decreased risk of nasopharyngeal carcinoma when compared with ?667TT homozygote (OR = 0.639, 95 % CI = 0.452–0.903, p = 0.011 for ?667CT; and OR = 0.441, 95 % CI = 0.213–0.915, p = 0.038 for ?667CC, respectively). In the ?842G>C polymorphism, compared with ?842GG homozygote, only ?842CG heterozygote but not ?842CC homozygote had a significantly decreased risk of nasopharyngeal carcinoma (OR = 0.465, 95 % CI = 0.249–0.871, p = 0.010). Genotype in the two SNPs in patients showed no significant associations with the clinicopathologic features examined. Our study showed that the minor genotypes of PIN1 promoter (?667CT, ?667CC and ?842CG) were associated with decreased risk of NPC in a Chinese population, suggested that PIN1 promoter polymorphisms might play an important role in NPC carcinogenesis.     

Association of Interleukin-1 gene polymorphisms with central obesity and metabolic syndrome in a coronary heart disease population

The objective of this study was to determine whether single nucleotide polymorphisms (SNPs) in the Interleukin-1 (IL-1) gene family are associated with central obesity and metabolic syndrome in a coronary heart disease population. The IL-1α C-889T (rs1800587) and IL-1β +3954 (rs1143634) SNPs were studied in a Western Australian coronary heart disease (CHD) population (N = 556). Subjects who were TT homozygous at either SNP had larger waist circumference (IL-1α: 1.8 cm greater, P = 0.04; IL-1β: 4 cm greater, P = 0.0004) compared with major allele homozygotes. Individuals with two copies of the IL-1α:IL-1β T:T haplotype had greater waist circumference (4.7 cm greater, P = 0.0001) compared to other haplotypes. There was a significant interaction between the IL-1β SNP and BMI level on waist circumference (P = 0.01). When the cohort was stratified by median BMI, TT carriers for IL-1β with above median BMI had greater waist circumference (6.1 cm greater, P = 0.007) compared to baseline carriers, whilst no significant association was seen in the below median group. Similarly, when the cohort was stratified by median fibrinogen level (IL-1α interaction P = 0.01; IL-1β interaction P = 0.04), TT carriers for both SNPs in the above median fibrinogen group had greater waist circumference (IL-1α 2.7 cm greater, P = 0.007; IL-1β 3.3 cm greater, P = 0.003) compared with major allele homozygotes. This association was not seen in the below median group. Also, we found a trend of increased metabolic syndrome for IL-1β TT homozygotes (P = 0.07). In conclusion, our findings suggest that in a CHD population IL-1 gene polymorphisms may be involved in increased central obesity, and the genetic influences are more evident among patients who have a higher level of obesity or inflammatory markers.     

GT-repeat polymorphism in the heme oxygenase-1 gene promoter and the risk of carotid atherosclerosis related to arsenic exposure

Communication between the SR (sarcoplasmic reticulum, SR) and mitochondria is important for cell survival and apoptosis. The SR supplies Ca²⁺ directly to mitochondria via inositol 1,4,5-trisphosphate receptors (IP₃Rs) at close contacts between the two organelles referred to as mitochondrion-associated ER membrane (MAM). Although it has been demonstrated that CaR (calcium sensing receptor) activation is involved in intracellular calcium overload during hypoxia/reoxygenation (H/Re), the role of CaR activation in the cardiomyocyte apoptotic pathway remains unclear. We postulated that CaR activation plays a role in the regulation of SR-mitochondrial inter-organelle Ca²⁺ signaling, causing apoptosis during H/Re. To investigate the above hypothesis, cultured cardiomyocytes were subjected to H/Re. We examined the distribution of IP₃Rs in cardiomyocytes via immunofluorescence and Western blotting and found that type 3 IP₃Rs were located in the SR. [Ca²⁺]i, [Ca²⁺]_m and [Ca²⁺]_SR were determined using Fluo-4, x-rhod-1 and Fluo 5N, respectively, and the mitochondrial membrane potential was detected with JC-1 during reoxygenation using laser confocal microscopy. We found that activation of CaR reduced [Ca²⁺]_SR, increased [Ca²⁺]_i and [Ca²⁺]_m and decreased the mitochondrial membrane potential during reoxygenation. We found that the activation of CaR caused the cleavage of BAP31, thus generating the pro-apoptotic p20 fragment, which induced the release of cytochrome c from mitochondria and the translocation of bak/bax to mitochondria. Taken together, these results reveal that CaR activation causes Ca²⁺ release from the SR into the mitochondria through IP₃Rs and induces cardiomyocyte apoptosis during hypoxia/reoxygenation.     

Association between polymorphisms in AXIN1 gene and atrial septal defect

Abstract

Context: AXIN1 is a central component of Wnt signalling pathway which is essential for embryonic development.

Objective: To investigate whether polymorphisms of AXIN1 contribute to ASD susceptibility.

Materials and methods: Three tag SNPs (rs12921862, rs370681 and rs1805105) in AXIN1 were genotyped in 208 ASD patients and 302 healthy controls using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) in a Chinese population.

Results: Significantly increased ASD risk was observed to be associated with the A allele of rs12921862 (p?<?0.0001, OR?=?3.096, 95% CI?=?2.037–4.717). Increased ASD risk was observed to be associated with rs370681 in a codominant (p?=?0.043, OR?=?1.52, 95% CI?=?1.04–2.22) and overdominant model (p?=?0.016, OR?=?1.57, 95% CI?=?1.08–2.27).

Conclusion: rs12921862 and rs370681 may contribute to ASD susceptibility.     

Microsatellite polymorphism in the human heme oxygenase-1 gene promoter and its application in association studies with Alzheimer and Parkinson disease

Oxidative stress has been suggested to be involved in the pathogenesis of neurodegenerative diseases, such as Alzheimer disease (AD) and Parkinson disease (PD). Heme oxygenase-1 (HO-1), a key enzyme in heme catabolism, also functions as an antioxidant enzyme. Here, we show that a (GT)_n repeat in the human HO-1 gene promoter region is highly polymorphic, although no particular alleles are associated with AD or PD. This newly identified genetic marker should allow us to study the possible involvement of HO-1 in certain human diseases. Received: 5 November 1996 / Accepted: 18 February 1997     

Association between polymorphisms of the CYP11A1 gene and polycystic ovary syndrome in Chinese women

The cholesterol side chain cleavage enzyme (CYP11A1) gene plays an important part in the synthesis of sex hormones and has been reported to be involved in the pathogenesis of polycystic ovary syndrome. A case-control study including 314 PCOS patients and 314 controls was conducted to assess the association of the SNPs rs4077582 and rs11632698 in CYP11A1 with PCOS using the polymerase chain reaction-restriction fragment length polymorphism method. Thereafter, 100 DNA samples were re-genotyped by direct sequencing for confirmation. The genotypic distribution of rs4077582 in women with PCOS differed from that in controls (P = 0.002). No such distributional difference was found in rs11632698 (P = 0.912). Data from our previous study of these two SNPs in another population including 290 PCOS patients and 344 controls was combined with the current data. Combined analysis (a total of 1262 participants, including 604 PCOS patients and 658 control women) showed a much more significant difference in the genotypic distribution of rs4077582 between PCOS and controls (P < 0.001). The T allele was more prevalent in PCOS patients (Odds ratio = 1.314; 95 % CI 1.122-1.540). The testosterone levels among the three genotypes for rs4077582 were different in the control group, as were the LH levels and the LH/FSH ratio. Therefore, SNP rs4077582 in CYP11A1 is strongly associated with susceptibility to PCOS and may alter the testosterone levels by the regulation of LH in different genotypes. No association was observed in rs11632698.     

Shorter GT repeat polymorphism in the heme oxygenase-1 gene promoter has protective effect on ischemic stroke in dyslipidemia patients

Background  

The microsatellite polymorphism of heme oxygenase (HO)-1 gene promoter has been shown to be associated with the susceptibility to ischemic event, including coronary artery disease (CAD), myocardial infarction, and peripheral vascular disease. We aimed to examine whether the length of (GT)_n repeats in HO-1 gene promoter is associated with ischemic stroke in people with CAD risk factors, especially low level of HDL.     

Regulation of heme oxygenase-1 by nitric oxide during hepatopulmonary syndrome

During hepatopulmonary syndrome caused by liver cirrhosis, pulmonary endothelial nitric oxide (NO) synthase (NOS) expression and NO production are increased. Increased NO contributes to the blunted hypoxic pressor response (HPR) during cirrhosis and may induce heme oxygenase-1 (HO-1) expression and carbon monoxide (CO) production, exacerbating the blunted HPR. We hypothesized that NO regulates the expression of HO-1 during cirrhosis, contributing to hepatopulmonary syndrome. Cirrhosis was induced in rats by common bile duct ligation (CBDL). Rats were studied 2 and 5 wk after CBDL or sham surgery. Lung HO-1 expression was elevated 5 wk after CBDL. Liver HO-1 was increased at 2 wk and remained elevated at 5 wk. In catheterized rats, the blunted HPR was partially restored by HO inhibition. Rats treated with the NOS inhibitor N(G)-nitro-L-arginine methyl ester for the entire 2- or 5-wk duration had normalized HO-1 expression and HPR. These data provide in vivo evidence for the NO-mediated upregulation of HO-1 expression and support the concept that hepatopulmonary syndrome is multifactorial, involving not only NO, but also HO-1 and CO.     

Association between restless legs syndrome and CLOCK and NPAS2 gene polymorphisms in schizophrenia

Previous studies have suggested that there is a genetic basis to restless legs syndrome (RLS) development. Occurrence of antipsychotic-induced RLS could also be due to differences in genetic susceptibility. We investigated whether CLOCK and NPAS2 gene polymorphisms are associated with RLS in schizophrenic patients on antipsychotics because RLS symptoms usually manifest during the evening and night. We assessed symptoms of RLS in 190 Korean schizophrenic patients on antipsychotics and divided the subjects into two groups according to the International Restless Legs Syndrome Study Group diagnostic criteria: (i) subjects who met all the criteria and (ii) the remaining subjects who did not meet all the criteria. We found a significant difference in the number of subjects with different genotype and allele carrier frequencies for the CLOCK gene (rs2412646) between the two groups (p?=?0.031 and 0.010, respectively). Distribution of CLOCK haplotypes (rs2412646–rs1801260) was significantly different between schizophrenic patients with and without RLS (p?=?0.021). However, the distributions of allelic, genotypic, and haplotypic variants of NPAS2 (rs2305160 and rs6725296) were not significantly different between the two groups. Our results suggest that CLOCK polymorphisms are associated with increased susceptibility of schizophrenic patients to RLS. We hypothesize that RLS in schizophrenia patients treated with antipsychotics may be a very mild akathisia that manifests during the night and is under control of circadian oscillation.